Added sRGB formats to PixelFormats + R and RG sRGB GL texture formats.

The extension support is a mess, as usual. This time the ES flavor
supports something that desktop doesn't and WebGL lack those altogether.
Yay.

doc/changelog.dox

@@ -54,6 +54,10 @@ See also:
     @ref CompressedPixelFormat as well as their conversion to corresponding
     GL/Vulkan formats in @ref GL::compressedPixelFormat() and
     @ref Vk::vkFormat(Magnum::CompressedPixelFormat)
+-   New @ref PixelFormat::R8Srgb, @ref PixelFormat::RG8Srgb,
+    @ref PixelFormat::RGB8Srgb and @ref PixelFormat::RGBA8Srgb sRGB pixel
+    formats as well as their conversion to corresponding GL/Vulkan formats in
+    @ref GL::pixelFormat() and @ref Vk::vkFormat(Magnum::PixelFormat)
 
 @subsubsection changelog-latest-new-audio Audio library
 
@@ -107,6 +111,10 @@ See also:
     -   PVRTC formats defined by the @gl_extension{IMG,texture_compression_pvrtc}
         / @gl_extension{IMG,pvrtc_sRGB} OpenGL ES and
         @webgl_extension{WEBGL,compressed_texture_pvrtc} WebGL extensions
+-   Implemented @gl_extension{EXT,texture_sRGB_R8} and
+    @gl_extension{EXT,texture_sRGB_RG8} extensions adding
+    @ref GL::TextureFormat::SR8 and @ref GL::TextureFormat::SRG8 formats to
+    complement new sRGB formats in @ref GL::PixelFormat
 -   New @ref GL::AbstractFramebuffer::implementationColorReadFormat() and
     @ref GL::AbstractFramebuffer::implementationColorReadType() queries for
     more robust checks when doing framebuffer readbacks; together with three

doc/opengl-support.dox

@@ -319,6 +319,7 @@ Extension                                   | Status
 @gl_extension{EXT,shader_integer_mix}       | done (shading language only)
 @gl_extension{EXT,debug_label}              | missing pipeline and sampler label
 @gl_extension{EXT,debug_marker}             | done
+@gl_extension{EXT,sRGB_R8}                  | done
 @gl_extension{GREMEDY,string_marker}        | done
 
 @subsection opengl-support-es20 OpenGL ES 2.0
@@ -461,6 +462,8 @@ Extension                                   | Status
 @gl_extension{EXT,texture_compression_s3tc} | done
 @gl_extension{EXT,pvrtc_sRGB}               | done
 @gl_extension{EXT,shader_integer_mix}       | done (shading language only)
+@gl_extension{EXT,sRGB_R8}                  | done
+@gl_extension{EXT,sRGB_RG8}                 | done
 @gl_extension{EXT,polygon_offset_clamp}     | |
 @gl_extension{EXT,texture_compression_rgtc} | done
 @gl_extension{EXT,texture_compression_bptc} | done

src/Magnum/DebugTools/CompareImage.cpp

@@ -121,11 +121,19 @@ std::tuple<Containers::Array<Float>, Float, Float> calculateImageDelta(const Pix
                     Containers::arrayCast<2, const Math::Vector<size, T>>(actualPixels), \
                     expected.pixels<Math::Vector<size, T>>(), delta);       \
                 break;
+        #define _e(first, second, third, size, T)                           \
+            case PixelFormat::first:                                        \
+            case PixelFormat::second:                                       \
+            case PixelFormat::third:                                        \
+                max = calculateImageDelta<size, T>(                         \
+                    Containers::arrayCast<2, const Math::Vector<size, T>>(actualPixels), \
+                    expected.pixels<Math::Vector<size, T>>(), delta);       \
+                break;
         /* LCOV_EXCL_START */
-        _d(R8Unorm, R8UI, 1, UnsignedByte)
+        _e(R8Unorm, R8Srgb, R8UI, 1, UnsignedByte)
-        _d(RG8Unorm, RG8UI, 2, UnsignedByte)
+        _e(RG8Unorm, RG8Srgb, RG8UI, 2, UnsignedByte)
-        _d(RGB8Unorm, RGB8UI, 3, UnsignedByte)
+        _e(RGB8Unorm, RGB8Srgb, RGB8UI, 3, UnsignedByte)
-        _d(RGBA8Unorm, RGBA8UI, 4, UnsignedByte)
+        _e(RGBA8Unorm, RGBA8Srgb, RGBA8UI, 4, UnsignedByte)
         _d(R8Snorm, R8I, 1, Byte)
         _d(RG8Snorm, RG8I, 2, Byte)
         _d(RGB8Snorm, RGB8I, 3, Byte)
@@ -151,6 +159,7 @@ std::tuple<Containers::Array<Float>, Float, Float> calculateImageDelta(const Pix
         _c(RGB32F, 3, Float)
         _c(RGBA32F, 4, Float)
         /* LCOV_EXCL_STOP */
+        #undef _e
         #undef _d
         #undef _c
 
@@ -246,12 +255,18 @@ void printPixelAt(Debug& out, const Containers::StridedArrayView3D<const char>&
             case PixelFormat::second:                                       \
                 out << *reinterpret_cast<const Math::Vector<size, T>*>(pixel); \
                 break;
+        #define _e(first, second, third, size, T)                           \
+            case PixelFormat::first:                                        \
+            case PixelFormat::second:                                       \
+            case PixelFormat::third:                                       \
+                out << *reinterpret_cast<const Math::Vector<size, T>*>(pixel); \
+                break;
         /* LCOV_EXCL_START */
-        _d(R8Unorm, R8UI, 1, UnsignedByte)
+        _e(R8Unorm, R8Srgb, R8UI, 1, UnsignedByte)
-        _d(RG8Unorm, RG8UI, 2, UnsignedByte)
+        _e(RG8Unorm, RG8Srgb, RG8UI, 2, UnsignedByte)
         _c(RGB8UI, 3, UnsignedByte)
         _c(RGBA8UI, 4, UnsignedByte)
-        /* RGB8Unorm, RGBA8Unorm handled below */
+        /* RGB8Unorm, RGBA8Unorm, RGB8Srgb, RGBA8Srgb handled below */
         _d(R8Snorm, R8I, 1, Byte)
         _d(RG8Snorm, RG8I, 2, Byte)
         _d(RGB8Snorm, RGB8I, 3, Byte)
@@ -277,14 +292,17 @@ void printPixelAt(Debug& out, const Containers::StridedArrayView3D<const char>&
         _c(RGB32F, 3, Float)
         _c(RGBA32F, 4, Float)
         /* LCOV_EXCL_STOP */
+        #undef _e
         #undef _d
         #undef _c
 
         /* Take the opportunity and print 8-bit colors in hex */
         case PixelFormat::RGB8Unorm:
+        case PixelFormat::RGB8Srgb:
             out << *reinterpret_cast<const Color3ub*>(pixel);
             break;
         case PixelFormat::RGBA8Unorm:
+        case PixelFormat::RGBA8Srgb:
             out << *reinterpret_cast<const Color4ub*>(pixel);
             break;
 

src/Magnum/GL/AbstractTexture.cpp

@@ -550,6 +550,9 @@ PixelFormat pixelFormatForInternalFormat(const TextureFormat internalFormat) {
         #ifndef MAGNUM_TARGET_GLES2
         case TextureFormat::R8Snorm:
         #endif
+        #ifndef MAGNUM_TARGET_WEBGL
+        case TextureFormat::SR8:
+        #endif
         #ifndef MAGNUM_TARGET_GLES
         case TextureFormat::R16:
         case TextureFormat::R16Snorm:
@@ -597,6 +600,9 @@ PixelFormat pixelFormatForInternalFormat(const TextureFormat internalFormat) {
         #ifndef MAGNUM_TARGET_GLES2
         case TextureFormat::RG8Snorm:
         #endif
+        #ifdef MAGNUM_TARGET_GLES
+        case TextureFormat::SRG8:
+        #endif
         #ifndef MAGNUM_TARGET_GLES
         case TextureFormat::RG16:
         case TextureFormat::RG16Snorm:
@@ -895,6 +901,12 @@ PixelType pixelTypeForInternalFormat(const TextureFormat internalFormat) {
         case TextureFormat::Luminance:
         case TextureFormat::LuminanceAlpha:
         #endif
+        #ifndef MAGNUM_TARGET_WEBGL
+        case TextureFormat::SR8:
+        #ifdef MAGNUM_TARGET_GLES
+        case TextureFormat::SRG8:
+        #endif
+        #endif
         #if !defined(MAGNUM_TARGET_GLES) || defined(MAGNUM_TARGET_GLES2)
         case TextureFormat::SRGB:
         case TextureFormat::SRGBAlpha:

src/Magnum/GL/Context.cpp

@@ -95,6 +95,7 @@ constexpr Extension ExtensionList[]{
     _extension(EXT,shader_integer_mix),
     _extension(EXT,debug_label),
     _extension(EXT,debug_marker),
+    _extension(EXT,texture_sRGB_R8),
     _extension(GREMEDY,string_marker),
     _extension(KHR,texture_compression_astc_ldr),
     _extension(KHR,texture_compression_astc_hdr),
@@ -310,6 +311,8 @@ constexpr Extension ExtensionList[]{
     _extension(EXT,pvrtc_sRGB),
     #ifndef MAGNUM_TARGET_GLES2
     _extension(EXT,shader_integer_mix),
+    _extension(EXT,texture_sRGB_R8),
+    _extension(EXT,texture_sRGB_RG8),
     #endif
     _extension(EXT,polygon_offset_clamp),
     _extension(EXT,texture_compression_s3tc_srgb),

src/Magnum/GL/Extensions.h

@@ -238,6 +238,7 @@ namespace AMD {
     _extension(153,EXT,shader_integer_mix,              GL300,  None) // #437
     _extension(154,EXT,debug_label,                     GL210,  None) // #439
     _extension(155,EXT,debug_marker,                    GL210,  None) // #440
+    _extension(156,EXT,texture_sRGB_R8,                 GL210,  None) // #534
 } namespace GREMEDY {
     _extension(157,GREMEDY,string_marker,               GL210,  None) // #311
 } namespace KHR {
@@ -413,15 +414,17 @@ namespace ANDROID {
     _extension( 59,EXT,texture_buffer,              GLES310, GLES320) // #183
     _extension( 60,EXT,texture_cube_map_array,      GLES310, GLES320) // #184
     _extension( 61,EXT,primitive_bounding_box,      GLES310, GLES320) // #186
+    _extension( 62,EXT,texture_sRGB_R8,             GLES300,    None) // #221
+    _extension( 63,EXT,texture_sRGB_RG8,            GLES300,    None) // #223
     #endif
-    _extension( 62,EXT,polygon_offset_clamp,        GLES200,    None) // #252
+    _extension( 64,EXT,polygon_offset_clamp,        GLES200,    None) // #252
     #ifndef MAGNUM_TARGET_GLES2
-    _extension( 63,EXT,texture_compression_rgtc,    GLES300,    None) // #286
+    _extension( 65,EXT,texture_compression_rgtc,    GLES300,    None) // #286
-    _extension( 64,EXT,texture_compression_bptc,    GLES300,    None) // #287
+    _extension( 66,EXT,texture_compression_bptc,    GLES300,    None) // #287
     #endif
-    _extension( 65,EXT,texture_compression_s3tc_srgb, GLES200,  None) // #289
+    _extension( 67,EXT,texture_compression_s3tc_srgb, GLES200,  None) // #289
 } namespace IMG {
-    _extension( 66,IMG,texture_compression_pvrtc,   GLES200,    None) // #54
+    _extension( 68,IMG,texture_compression_pvrtc,   GLES200,    None) // #54
 } namespace KHR {
     _extension( 70,KHR,texture_compression_astc_ldr,GLES200, GLES320) // #117
     _extension( 71,KHR,texture_compression_astc_hdr,GLES200,    None) // #117

src/Magnum/GL/Implementation/pixelFormatMapping.hpp

@@ -47,6 +47,17 @@ _s(RG8Snorm)
 _s(RGB8Snorm)
 _s(RGBA8Snorm)
 #endif
+/* Yes, GL's pixel format doesn't distinguish between linear and sRGB, so
+   mapping is the same as in case of the Unorm types. */
+#ifndef MAGNUM_TARGET_GLES2
+_c(R8Srgb, Red, UnsignedByte)
+_c(RG8Srgb, RG, UnsignedByte)
+#else
+_c(R8Srgb, Luminance, UnsignedByte)
+_c(RG8Srgb, LuminanceAlpha, UnsignedByte)
+#endif
+_c(RGB8Srgb, RGB, UnsignedByte)
+_c(RGBA8Srgb, RGBA, UnsignedByte)
 #ifndef MAGNUM_TARGET_GLES2
 _c(R8UI, RedInteger, UnsignedByte)
 _c(RG8UI, RGInteger, UnsignedByte)

src/Magnum/GL/TextureFormat.h

@@ -767,6 +767,31 @@ enum class TextureFormat: GLenum {
     LuminanceAlpha = GL_LUMINANCE_ALPHA,
     #endif
 
+    #ifndef MAGNUM_TARGET_WEBGL
+    /**
+     * sRGB-encoded red component, normalized unsigned byte.
+     * @requires_extension Extension @gl_extension{EXT,texture_sRGB_R8}
+     * @requires_es_extension Extension @gl_extension{EXT,texture_sRGB_R8}
+     * @requires_gles One- and two-component sRGB texture formats are not
+     *      available in WebGL, use @ref TextureFormat::SRGB8 or
+     *      @ref TextureFormat::SRGB8Alpha8
+     */
+    SR8 = GL_SR8_EXT,
+
+    #if defined(MAGNUM_TARGET_GLES) || defined(DOXYGEN_GENERATING_OUTPUT)
+    /**
+     * sRGB-encoded red and green component, normalized unsigned byte.
+     * @requires_es_extension Extension @gl_extension{EXT,texture_sRGB_RG8}
+     * @requires_gles One- and two-component sRGB texture formats are not
+     *      available in WebGL, use @ref TextureFormat::SRGB8 or
+     *      @ref TextureFormat::SRGB8Alpha8 instead. Only
+     *      @ref TextureFormat::SR8, @ref TextureFormat::SRGB8 or
+     *      @ref TextureFormat::SRGB8Alpha8 is available in desktop OpenGL.
+     */
+    SRG8 = GL_SRG8_EXT,
+    #endif
+    #endif
+
     #ifndef MAGNUM_TARGET_GLES
     /**
      * RGB, normalized unsigned, red and green component 3bit, blue 2bit.

src/Magnum/PixelFormat.cpp

@@ -41,11 +41,13 @@ UnsignedInt pixelSize(const PixelFormat format) {
     switch(format) {
         case PixelFormat::R8Unorm:
         case PixelFormat::R8Snorm:
+        case PixelFormat::R8Srgb:
         case PixelFormat::R8UI:
         case PixelFormat::R8I:
             return 1;
         case PixelFormat::RG8Unorm:
         case PixelFormat::RG8Snorm:
+        case PixelFormat::RG8Srgb:
         case PixelFormat::RG8UI:
         case PixelFormat::RG8I:
         case PixelFormat::R16Unorm:
@@ -56,11 +58,13 @@ UnsignedInt pixelSize(const PixelFormat format) {
             return 2;
         case PixelFormat::RGB8Unorm:
         case PixelFormat::RGB8Snorm:
+        case PixelFormat::RGB8Srgb:
         case PixelFormat::RGB8UI:
         case PixelFormat::RGB8I:
             return 3;
         case PixelFormat::RGBA8Unorm:
         case PixelFormat::RGBA8Snorm:
+        case PixelFormat::RGBA8Srgb:
         case PixelFormat::RGBA8UI:
         case PixelFormat::RGBA8I:
         case PixelFormat::RG16Unorm:
@@ -124,6 +128,10 @@ Debug& operator<<(Debug& debug, const PixelFormat value) {
         _c(RG8Snorm)
         _c(RGB8Snorm)
         _c(RGBA8Snorm)
+        _c(R8Srgb)
+        _c(RG8Srgb)
+        _c(RGB8Srgb)
+        _c(RGBA8Srgb)
         _c(R8UI)
         _c(RG8UI)
         _c(RGB8UI)

src/Magnum/PixelFormat.h

@@ -130,6 +130,42 @@ enum class PixelFormat: UnsignedInt {
      */
     RGBA8Snorm,
 
+    /**
+     * sRGB-encoded red component, normalized unsigned byte.
+     *
+     * Corresponds to @ref GL::PixelFormat::Red and
+     * @ref GL::PixelType::UnsignedByte, @ref GL::TextureFormat::SR8 /
+     * @def_vk_keyword{FORMAT_R8_SRGB,Format}.
+     */
+    R8Srgb,
+
+    /**
+     * sRGB-encoded red and green component, normalized unsigned byte.
+     *
+     * Corresponds to @ref GL::PixelFormat::RG and
+     * @ref GL::PixelType::UnsignedByte, @ref GL::TextureFormat::SRG8 /
+     * @def_vk_keyword{FORMAT_R8G8_SRGB,Format}.
+     */
+    RG8Srgb,
+
+    /**
+     * sRGB, normalized unsigned byte.
+     *
+     * Corresponds to @ref GL::PixelFormat::RGB and
+     * @ref GL::PixelType::UnsignedByte, @ref GL::TextureFormat::SRGB8 /
+     * @def_vk_keyword{FORMAT_R8G8B8_SRGB,Format}.
+     */
+    RGB8Srgb,
+
+    /**
+     * sRGB + linear alpha, normalized unsigned byte.
+     *
+     * Corresponds to @ref GL::PixelFormat::RGBA and
+     * @ref GL::PixelType::UnsignedByte, @ref GL::TextureFormat::SRGB8Alpha8 /
+     * @def_vk_keyword{FORMAT_R8G8B8A8_SRGB,Format}.
+     */
+    RGBA8Srgb,
+
     /**
      * Red component, integral unsigned byte.
      *

src/Magnum/Vk/Implementation/formatMapping.hpp

@@ -33,6 +33,10 @@ _c(R8Snorm, R8_SNORM)
 _c(RG8Snorm, R8G8_SNORM)
 _c(RGB8Snorm, R8G8B8_SNORM)
 _c(RGBA8Snorm, R8G8B8A8_SNORM)
+_c(R8Srgb, R8_SRGB)
+_c(RG8Srgb, R8G8_SRGB)
+_c(RGB8Srgb, R8G8B8_SRGB)
+_c(RGBA8Srgb, R8G8B8A8_SRGB)
 _c(R8UI, R8_UINT)
 _c(RG8UI, R8G8_UINT)
 _c(RGB8UI, R8G8B8_UINT)

src/MagnumExternal/OpenGL/GL/extensions.txt

@@ -30,6 +30,7 @@ extension EXT_texture_sRGB_decode               optional
 extension EXT_shader_integer_mix                optional
 extension EXT_debug_label                       optional
 extension EXT_debug_marker                      optional
+extension EXT_texture_sRGB_R8                   optional
 extension GREMEDY_string_marker                 optional
 extension KHR_texture_compression_astc_ldr      optional
 # extension KHR_texture_compression_astc_hdr    optional

src/MagnumExternal/OpenGL/GL/flextGL.h

@@ -1701,6 +1701,10 @@ typedef void (APIENTRY *GLDEBUGPROC)(GLenum source,GLenum type,GLuint id,GLenum
 #define GL_SAMPLER 0x82E6
 #define GL_TRANSFORM_FEEDBACK 0x8E22
 
+/* GL_EXT_texture_sRGB_R8 */
+
+#define GL_SR8_EXT 0x8FBD
+
 /* GL_KHR_texture_compression_astc_ldr */
 
 #define GL_COMPRESSED_RGBA_ASTC_4x4_KHR 0x93B0

src/MagnumExternal/OpenGL/GLES2/extensions.txt

@@ -86,6 +86,8 @@ extension EXT_texture_sRGB_decode               optional
 extension EXT_sRGB_write_control                optional
 extension EXT_texture_compression_s3tc          optional
 extension EXT_pvrtc_sRGB                        optional
+extension EXT_texture_sRGB_R8                   optional
+extension EXT_texture_sRGB_RG8                  optional
 extension EXT_polygon_offset_clamp              optional
 extension EXT_texture_compression_s3tc_srgb     optional
 extension IMG_texture_compression_pvrtc         optional

src/MagnumExternal/OpenGL/GLES2/flextGL.h

@@ -976,6 +976,14 @@ typedef void (APIENTRY *GLDEBUGPROCKHR)(GLenum source,GLenum type,GLuint id,GLen
 #define GL_COMPRESSED_SRGB_ALPHA_PVRTC_2BPPV2_IMG 0x93F0
 #define GL_COMPRESSED_SRGB_ALPHA_PVRTC_4BPPV2_IMG 0x93F1
 
+/* GL_EXT_texture_sRGB_R8 */
+
+#define GL_SR8_EXT 0x8FBD
+
+/* GL_EXT_texture_sRGB_RG8 */
+
+#define GL_SRG8_EXT 0x8FBE
+
 /* GL_EXT_polygon_offset_clamp */
 
 #define GL_POLYGON_OFFSET_CLAMP_EXT 0x8E1B

src/MagnumExternal/OpenGL/GLES2/flextGLWindowsDesktop.h

@@ -971,6 +971,14 @@ typedef void (APIENTRY *GLDEBUGPROCKHR)(GLenum source,GLenum type,GLuint id,GLen
 #define GL_COMPRESSED_SRGB_ALPHA_PVRTC_2BPPV2_IMG 0x93F0
 #define GL_COMPRESSED_SRGB_ALPHA_PVRTC_4BPPV2_IMG 0x93F1
 
+/* GL_EXT_texture_sRGB_R8 */
+
+#define GL_SR8_EXT 0x8FBD
+
+/* GL_EXT_texture_sRGB_RG8 */
+
+#define GL_SRG8_EXT 0x8FBE
+
 /* GL_EXT_polygon_offset_clamp */
 
 #define GL_POLYGON_OFFSET_CLAMP_EXT 0x8E1B

src/MagnumExternal/OpenGL/GLES3/extensions.txt

@@ -53,6 +53,8 @@ extension EXT_sRGB_write_control                    optional
 extension EXT_texture_compression_s3tc              optional
 extension EXT_pvrtc_sRGB                            optional
 extension EXT_shader_integer_mix                    optional
+extension EXT_texture_sRGB_R8                       optional
+extension EXT_texture_sRGB_RG8                      optional
 extension EXT_polygon_offset_clamp                  optional
 extension EXT_texture_compression_rgtc              optional
 extension EXT_texture_compression_bptc              optional

src/MagnumExternal/OpenGL/GLES3/flextGL.h

@@ -1504,6 +1504,14 @@ typedef void (APIENTRY *GLDEBUGPROCKHR)(GLenum source,GLenum type,GLuint id,GLen
 #define GL_COMPRESSED_SRGB_ALPHA_PVRTC_2BPPV2_IMG 0x93F0
 #define GL_COMPRESSED_SRGB_ALPHA_PVRTC_4BPPV2_IMG 0x93F1
 
+/* GL_EXT_texture_sRGB_R8 */
+
+#define GL_SR8_EXT 0x8FBD
+
+/* GL_EXT_texture_sRGB_RG8 */
+
+#define GL_SRG8_EXT 0x8FBE
+
 /* GL_EXT_polygon_offset_clamp */
 
 #define GL_POLYGON_OFFSET_CLAMP_EXT 0x8E1B

src/MagnumExternal/OpenGL/GLES3/flextGLWindowsDesktop.h

@@ -1496,6 +1496,14 @@ typedef void (APIENTRY *GLDEBUGPROCKHR)(GLenum source,GLenum type,GLuint id,GLen
 #define GL_COMPRESSED_SRGB_ALPHA_PVRTC_2BPPV2_IMG 0x93F0
 #define GL_COMPRESSED_SRGB_ALPHA_PVRTC_4BPPV2_IMG 0x93F1
 
+/* GL_EXT_texture_sRGB_R8 */
+
+#define GL_SR8_EXT 0x8FBD
+
+/* GL_EXT_texture_sRGB_RG8 */
+
+#define GL_SRG8_EXT 0x8FBE
+
 /* GL_EXT_polygon_offset_clamp */
 
 #define GL_POLYGON_OFFSET_CLAMP_EXT 0x8E1B